ATTACH + Posting data to an API from my custom App

I have created a Dedicated Attached Webhook for a Instant Trigger module of my custom app.
This is my code. and I try to send data, webhook url to an API. but The request was accepted. Waiting for data.

// // Uncomment and update the following lines to implement the “attach” method.
// Request
“url”: “{{parameters.service}}/webhooks”,
“method”: “POST”,
“headers”: {
“Accept”: “/”,
“Accept-Encoding”: “gzip, deflate, br”,
“Connection”: “keep-alive”,
“x-api-key”: “xxxxxxxxxxxxxxxxxxxxxxxx”,
“deviceid”: “xhhxxhhxx”,
“cname”: “”,
“Content-Type”: “application/json”
// “Content-Type”: “application/x-www-form-urlencoded”
“body”: {
“url”: “{{webhook.url}}”,
“events”: “test2,test2”
// “events”: “{{}}”

	// Response handling
	"response": {
		"output": "{{body}}",

		"error": {   
			// "type": "{{body.code}}",                                     // Error handling
			"message": "{{body.errors}}"  // On error, returns error message as "[statusCode] error text".


Did anybody manage to use the ATTACH functionality of webhooks?

Thanks in advance for your help!